Generally, a cutting insert is fastened to a cutting tool provided on a machine tool and used for cutting a workpiece that is generally formed of ferrous or nonferrous metals, non-metal material, and so on.
Generally, such cutting insert includes an upper surface, a lower surface, and a plurality of lateral surfaces connecting the upper surface and the lower surface. An upper cutting edge is provided between the lateral surface and the upper surface, and a lower cutting is provided between the lateral surface and the lower surface.
Referring to FIGS. 8 to 10, US2011/0103905 A1 illustrates a cutting insert and a tool holder. For reference, FIGS. 8 to 10 each correspond to FIGS. 1, 4, and 6 of US2011/0103905 A1 mentioned above, and the same reference numerals are used for convenience of explanation.
The cutting insert mentioned above is a double-sided circular insert 10 which is provided on a pocket of the tool holder, and which includes a plurality of first protrusions 26 formed on a first inner surface 24 of a circular upper portion 12, and a plurality of second protrusions 36 formed on a second inner surface 34, for mating with a plurality of dimples (not illustrated) formed in a pocket of the tool holder. Accordingly, because the round cutting insert 10 provided on the tool holder 40 has a circular shape, rotation torque is applied due to reaction force thereof during processing of the workpiece, but a plurality of first or second protrusions 26 or 36 mated with a plurality of dimples formed in the pocket 42 of the tool holder 40 (in a double-sided cutting insert, a plurality of first protrusions 26 may be mated with a plurality of dimples 48 or a plurality of second protrusions 36 may be mated with the dimples 48) may prevent the insert 10 from rotating from the tool holder 40 even under the rotation torque by the tool holder 40.
However, in the insert 10 of a related technology, a plurality of first or second protrusions 26 or 36 mated with a plurality of dimples 48 of the pocket 42 are formed not on a circumferential surface 16 of the insert 10, but on a first inner surface 24 of an insert upper portion 12 or on a second dinner surface 34 of an insert lower portion 14 which has a relatively narrower area. Accordingly, it is difficult to ensure a sufficient area for mating between the insert 10 and the pocket 42, thus causing problem of the insert 10 being unstably provided.